Al Filan, a teacher at Brother Rice High School for over 39 years, was found dead Tuesday morning in his Orland Park home.
Funeral arrangements are pending.
Filan was the school's business department chairman along with teaching business. He also coached soccer at Victor J. Andrew High School.
In a post on the Brother Rice website, Filan was described having "touched the lives of thousands of students, colleagues and family members; he will be fondly missed."